Molecular epidemiology of Saccharomyces cerevisiae in an immunocompromised host unit

Saccharomyces cerevisiae is increasingly recognized clinically, and repeated isolations from patients on a hematology unit in Turku, Finland, led to an epidemiologic investigation. Isolates were recovered from multiple body sites of 23 patients (n = 180) from 1994 to 1995 and from 29 patients (n = 45) from 1997 to 2002; these plus 2 from the hospital kitchen were identified as S. cerevisiae. Isolates were genotyped by restriction fragment length polymorphism (RFLP) of genomic DNA after EcoR1 digestion. Of 108 isolates, 97 (95 patient isolates and 2 from the hospital kitchen) were DNA group B and identical in RFLP pattern. The remaining 11 isolates were DNA group A; 2 patients that shared a room had identical group A isolates, both converted to DNA group B type colonization within 2 months. In almost all patients, S. cerevisiae was first recovered after admission. These data suggest an endemic source of colonizing organisms, possibly from the hospital food preparation area.